[RISCV] Add intrinsics for vmv.v.v, vmv.v.x, and vmv.x.i

We work with @rogfer01 from BSC to come out this patch.

Authored-by: Roger Ferrer Ibanez <rofirrim@gmail.com>
Co-Authored-by: Craig Topper <craig.topper@sifive.com>

Differential Revision: https://reviews.llvm.org/D93514